Soft tissues, such as tendons and ligaments, generally are attached to bone by small collagenous fibers. These fibers are strong, but permit the tendons and ligaments to be flexible. When soft tissue is torn away from the bone and requires repair, a surgeon is often required to repair the detached soft tissue with sutures which are attached to the bone by an anchor. These anchors are usually implanted into a patient's bone through extensive surgical procedures and more recently, through arthroscopic surgical techniques. Existing anchors are implanted into a patient's bone in a number of ways, which can generally be classified as those that require drilling of a hole in the bone, and those that can be implanted without drilling, such as pushed-in or screwed-in the bone, for example.
Once an anchor is implanted in a bone, a suture is typically passed through the soft tissue to be reattached, which suture is then secured to the anchor at the appropriate tension. Generally, some anchors may require a surgeon to tie a knot in the suture, or may be termed “knotless,” i.e., no knot is required to secure the soft tissue to the bone because a suture is retained by the anchor and the bone. The process of passing a suture through a soft tissue and tying a knot is time consuming and difficult to undertake in the tight space encountered during endoscopic surgery, and sometimes during conventional open surgery.
Anchor systems implanted by drilling a hole in the bone are complicated to use in that they require using multiple tools that must be inserted into the incision during the procedure, such as a separate insertion tool and a separate drilling tool. Such complex drilling anchor systems result in increased procedure times and added possibility of surgeon error during the extended procedures and tool switching.
Those skilled in the art will appreciate that anchors generally experience a wide range of stresses during insertion into a bone. Although some prior art anchors have attempted to incorporate polymeric materials in their construction, these anchors have, in practice, generally provided inadequate insertion and holding strengths. As a consequence, known anchor bodies and known bone-engaging means have generally been made from high strength, biocompatible metals, and metal alloys.
As the use of prior art anchoring devices has become more widespread, it has been found that known anchors suffer from a number of limitations. For example, forming both the anchor body and the bone-engaging means out of biocompatible metals and metal alloys increases the cost of manufacturing. Also, in many medical applications, it is desirable to minimize the metal remaining in the patient's body after surgery. Such metal may cause X-ray artifacts and may migrate due to patient rejection.
Due to the disadvantages of metal implants, a large number of different biocompatible polymeric and bioabsorbable materials have recently been developed and become widely used in medical implantations. Such materials are: (i) relatively low in cost; (ii) fully compatible with conventional fabrication methods; and (iii) capable of being absorbed into the body of the patient after surgery. There are several prior art anchors which are made of such materials.
At present, however, available polymeric and bioabsorbable materials generally do not possess the requisite mechanical properties to allow pushing in and adequate retention of the anchor in the bone without pre-drilling a hole in the bone and providing the anchor with some metal components. Some prior art anchors overcome this problem by providing anchors made of polymeric and bioabsorbable materials that have a metal tip strong enough to allow for the screwing-in or pushing-in of the anchor into the bone. However, a major disadvantage of such anchors is that the metal tip remains into the patient's bone, which increases the chances of anchor rejection and migration due to the patient's body rejecting the metal tip.
To this end, a need exists for a suture anchor system which allows a suture anchor to be implanted into bone with a single tool. It is to such a suture anchor system that the inventive concept disclosed herein is directed.